Method and apparatus for individually diverting selected sheets from a corrugator bridge

ABSTRACT

Apparatus and method for individually diverting sheets of corrugated paperboard from one of the bridges of a corrugator. A plurality of sheet diverting mechanisms are positioned between and below the conveyor belts of a corrugator bridge. A pivotally mounted sheet lifting arm is normally held down by a biasing air pressure on an air motor which operates the arm. When it is desired to divert a sheet, the biasing air pressure is removed, and a lower air pressure on the opposite side of a piston in the air motor starts to pivot the arm. However, the weight of sheets on the arm is sufficient to overcome the force of the lower air pressure and movement of the arm is stopped. When the sheet passes off of the arm, it is moved all the way up, tripping a valve which admits high-pressure air to hold the arm up. Thus, the next sheet in line is diverted from its path of travel. Either by operator action or by a preset timer, the high-pressure air is then removed, allowing subsequent sheets to force the arm downward again which, in part, resets the system for a future diverting cycle.

United States Patent 1 Di Frank et al.

[ 1 Oct. 30, 1973 [52] US. Cl. 209/74 R, 271/64 [51] Int. Cl. B07c 5/36 [58] Field of Search 271/64; 209/74, 88 S; 83/106 [56] References Cited 7 UNITED STATES PATENTS 2,556,895 6/1951 Baker 271/64 UX 2,756,050 7/1956 Matthews et al. 271/64 3,599,789 8/1971 Kurczak 209/74 Primary Examiner-Even C. Blunk Assistant Examiner-Bruce I-I. Stoner, Jr. Attorney-Steve M. McLary et al.

[57] ABSTRACT Apparatus and method for individually diverting sheets of corrugated paperboard from one of the bridges of a corrugator. A plurality of sheet diverting mechanisms are positioned between and below the conveyor belts of a corrugator bridge. A pivotally mounted sheet lifting arm is normally held down by a biasing air pressure on an air motor which operates the arm. When it is desired to divert a sheet, the biasing air pressure is removed, and a lower air pressure on the opposite side of a piston in the air motor starts to pivot the arm. However, the weight of sheets on the arm is sufiicient to overcome the force of the lower air pressure and movement of the arm is stopped. When the sheet passes off of the arm, it is moved all the way up, tripping a valve which admits high-pressure air to hold the arm up. Thus, the next sheet in line is diverted i' roin its path of travel. Either by operator action or by a preset timer, the high-pressure air is then removed, allowing'subsequent sheets to force the arm downward again which, in part, resets the system for a future diverting cycle.

16 Claims, 7 Drawing Figures METHOD AND APPARATUS FOR INDIVIDUALLY DIVERTING SELECTED SHEETS FROM A CORRUGATOR BRIDGE BACKGROUND OF THE INVENTION This invention generally relates to machines for the manufacture of corrugated paperboard. More particularly, this invention relates to apparatus and method for diverting sheets of paperboard from their path of travel on a bridge of such a machine. Most specifically, this invention relates to apparatus and method for diverting such sheets individually rather than as a unit.

Corrugated paperboard is manufactured in a continuous web as much as 80 or more inches wide. As a final stcp'in the manufacturing process, this continuous web is longitudinally slit into several strips of a lesser width. These strips are then transversely cut into individual sheets. The cutting mechanism shears'the strips on a diagonal. After the strips are cut into individual sheets, they are removed from the cutting knife by a conveyor carried by an upper or a lower bridge of the machine. This conveyor is running faster than the conveyor feeding the strips into the knife. The net result of the diagonal cut and the fast removal is that the sheets are conveyed along a bridge in a longitudinally spaced-apart pattern which exhibits a stair step type of edge. That is, multiple sheets are conveyed in side-by-side alignment with one another, but their leading and trailing edges are not aligned. When splices are made in the web of paperboard, those sheets which contain the splice must be diverted from the stream of sheets on a bridge to prevent jamming of subsequent handling equipment. In the prior art, a series of fingers carried on a common shaft were rotated into the path of travel of sheets to divert them simultaneously. However, the stair step edge pattern made timing and movement of this shaft difficult, since the fingers could contact the edge of one sheet too early or too late to divert it properly. We have devised an apparatus which senses the gap between successive sheets and moves a diverting arm or arms upward individually for each sheet, thus avoiding the problems of the single, fixed diverting system which contacted all of the sheets simultaneously.

SUMMARY OF THE INVENTION My invention is an apparatus and method for selectively, upwardly diverting sheets of corrugated paperboard from a bridge of a corrugator. The apparatus comprises a plurality of deflector members positioned at spaced intervals across the width of the bridge and normally below the path of travel of the sheets, power operated, deflector actuating means connected to each of said deflector members for moving said deflectors upwardly into sheet contacting position, and means responsive to movement of any individual deflector member to a predetermined upward position for maintaining said deflector member in fully-up, sheet deflecting position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, partially cut away, of one of the deflectors of the apparatus of the present invention;

FIG. 2 is a schematic diagram of the electrical control circuit of the apparatus of the present invention;

FIG. 3 is a schematic diagram ofthe pneumatic control circuit of the apparatus of the present invention;

FIG. 4 is a schematic, side elevation view of the apparatus of FIG. 1 inits rest" or retracted position;

FIG. 5 is a view similar to FIG. 4 with the apparatus shown in the"sensing position;

FIG. 6 is a view similar to FIG. 4 with the apparatus shown in the active position; and

FIG. 7 is a perspective view of a portion of a bridge of a corrugator, with the bridge supporting structure removed, illustrating the apparatus of the present invention in its operational environment.

DETAILED DESCRIPTION OF THE DRAWINGS The present invention finds its utility in a machine for the manufacture of corrugated paperboard, such machines generally being referred to as corrugators". In particular, this invention finds utility when used in conjunction with the invention disclosed in co-pending US Pat. Application Ser. No. 228,018 filed Feb. 22, 1972 and having a co-inventor in common with the present invention. Specifically, the invention disclosed in application Ser. No. 228,018 has proven to have an operational difficulty in that the sheets of corrugated paperboard which are cut by the rotary slitting knives in a corrugated paperboard machine exhibit a somewhat staggered pattern. That is, the sheets which emerge from the cutting knives are not uniformly aligned, but rather present a stair step type of longitudinal spacing as they proceed along the upper and lower bridges. This pattern is the result of two factors. First, the cutting knife is diagonally placed on the rotating cutting cylinder to achieve a shearing sort of action. Second, the removal conveyors carried by the upper and lower bridges run faster than the web of material entering the knives, thus accelerating individual cut sheets away from the knife or knives. Therefore, the deflecting fingers shown in patent application Ser. No. 228,018 have proven somewhat difficult to operate to achieve uniform results. The present invention overcomes this difficulty by allowing individual deflection of sheets rather than deflection of the entire width of the upper or lower bridge at a single time. The general operational environment of this invention may be seen in U.S. Pat. Application Ser. No. 228,018, the teachings of which are herein incorporated by reference.

FIG. 1 shows a single sheet deflection mechanism 10 in a partially cut away perspective view, so that the interrelation of the various parts of the sheet deflection mechanism 10 may be better understood. There are, in fact, a plurality of sheet deflection mechanisms 10 aligned across the width of the upper and/or the lower bridge of a corrugated paperboard machine. This may be seen by reference to FIG. 7. A main support member 12 has extending from it in a substantially horizontal plane a mounting plate 14. A reciprocating type air motor or air cylinder 16 is suspended below the mounting plate 14. The air motor 16 is of the type which has an operating rod 18 extending from one end thereof and has the other end thereof blind or closed. The air motor 16 is pivotally attached to a clevis mounting 20, which is fixed to the mounting plate 14. Thus, the air motor 16 is capable of a certain degree of relative rocking motion with respect to the mounting plate 14. Attached to and extending vertically upward from the mounting plate 14 is a pivot post 22, which is partially hidden in FIG. 1. A substantially L shaped sheet lifting arm or deflector member 24 has a leg portion 27 thereof pivotally mounted near the top of the pivot post 22 with a pivot pin 26 and a foot portion 25 substantially perpendicular to the leg portion 27. Thus, the sheet lifting arm 24 is free to rotate with respect to the pivot post 22. Near the lower end of the leg portion 27 of the sheet lifting arm 24, away from the pivot pin 26, a clevis mount 28 is attached to the leg portion 27. The extending end of the air motor rod 18 is fixed to the clevis mount 28. The net effect of the linkage thus described is that when the rod 18 is extended in the direction of the support member 12, the sheet lifting arm 24 is pivoted about its pivot pin 26 with the air motor 16 serving as a power means for pivoting the lifting arm 24. This motion is possible by virtue of the pivoting motion of the rod 18 in its clevis mount 28 and the movement of the air motor 16 about its clevis mount 20. Affixed to the extreme lower portion of the leg portion 27 is an operating cam 30. The operating cam 30 functions to control the movement of a cam follower 32 which is affixed to the operating stem 34 of a four-way valve 36. The valve 36 of which there are a plurality, as will be explained later) may be a model LR-0204 manufacturned by Numatics, Inc., Highland, Michigan 4803 1. When the rod 18 is fully retracted, the cam 30 is pulled back and forces the cam follower 32 and the operating stem 34 downward. When the rod 18 is extended, the cam 30 is moved forward and the cam follower 32 falls away from the influence of the cam 30, allowing the stem 34 to rise under the influence of a spring carried within the valve 36. The valve 36 is attached to a downwardly depending plate 38, which is attached to the underside of the mounting plate 14. It may be noted that the mounting plate 14 has a notched portion 40, which allows relatively free pivotal motion of the sheet lifting arm 24.

FIGS. 2 and 3 illustrate the electrical and pneumatic control system for the present invention. FIGS. 2 and 3 show a control means connected to the air motor 16 for: a) holding all of thelifting arms 24 in their rest position; b) substantially simultaneously moving all of the sheet lifting arms 24 into their sensing position when sheets are to be diverted; and c) individually moving the sheet lifting arms 24 into their active positions in response to a gap between successive sheets of paperboard. How these functions are accomplished will now be explained with reference to FIGS. 2 and 3. With particular reference to FIG. 3 first, a source of compressed air 42 is connected to a main inlet line 43. A branch line 44 is connected to a pressure regulator 46. The pressure regulator 46 is connected to an air manifold 48 by a pipeline 47. The manifold 48 is connected to a first inlet port of each of the valves 36 by a plurality of pipelines 49. It should be noted that the valve 36 is of the type such that when the stem 34 is depressed, the flow of air through the valve 36 is that shown in FIG. 3. However, a spring within the valve 36 will force the flow of air to that shown on the left side of the illustration of FIG. 3 of the valve 36 when the stem is released. The schematic view of FIG. 3 also shows that within the air motor 16 is a sliding piston 50, which is attached to and operates the rod 18. A first outlet port of the valve 36 is connected through a pipeline 52 to the blind end of the air motor 16. A second branch pipeline 54 connected to the main inlet line 43 is connected to a second air pressure regulator 55. The outlet of the second air pressure regulator 55 is through a pipeline 56, which is connected to a first inlet port of an electrically operated solenoid type four-way valve 58. The solenoid valve 58 may be a model 4JSA4 manufactured by Numatics, Inc., Highland, Michigan 48031.

In the normal or rest configuration, which is shown in FIG. 3, the pipeline 56 is connected through the valve 58 from a first outlet port to a pipeline 60. The pipeline 60 is connected to an air manifold 62, which in turn has a plurality of output pipes 63 connected to a second inlet port of each of the valves 36. The air pressure regulator 46 provides a low-pressure air supply in the range of approximately 4 pounds per square inch pressure. The second air pressure regulator 55 provides a high-pressure source of air in the range of approximately 60 pounds per square inch. Thus, of course, it is necessary that the source of compressed air 42 provide air at a pressure of at least 60 pounds per square inch. However, it should be clear that the absolute values of the relative pressures is not important, but what is important is that there be available a lowpressure air source and a high-pressure air source. The low-pressure air source should provide a net force on the lifting arm 24 slightly less than the net downward force of the moving sheets of paperboard, while the high-pressure source should provide such a force in excess of the net downward force of the moving sheets of paperboard, so as to be able to effect deflection of the sheets. In the configuration shown in FIG. 3, it is clear that the low-pressure air is entering the blind end of the air motor 16, thus attempting to push the piston 50 to the right, as seen in FIG. 3. However, a second outlet port of the valve 36 is also connected to the air motor 16 at the end opposite to the piston 50 through a pipeline 64. By tracing the path of the high-pressure air from the high-pressure air regulator 55, it may be seen that the high-pressure air is entering the air motor 16 through the pipeline 64 simultaneously with the lowpressure air through the pipeline 52. The net result is that the higher pressure air will maintain the piston 50 in .its position to the far left as seen in FIG. 3. This, of course, means that the rod 18 is retracted. It may be appreciated from FIG. 1 that with the rod 18 retracted, the foot portion 25 of the sheet lifting arm 24 is in substantially a horizontal position; this is the normal rest or nonoperating position of the foot portion 25. As a final connection shown in FIG. 3, a second outlet port of the valve 58 is connected to a pipeline 66, which is connected to yet a third air manifold 67. A plurality of pipelines 68 connects the air manifold 67 to a third inlet port of each of the valves 36. It may be appreciated that the third inlet port of the valve 58 to which the pipeline 68 is connected in FIG. 3 is a closed inlet, and therefore the pipelines 66 and 68 are inoperative during this particular stage of the operation of this device.

FIG. 2 shows, in a schematic ladder diagram, the electrical operating circuit for this invention. This is an electrical circuit means for energizing and deenergizing the solenoid valve 58. A source of electrical power 70 is connected through a transformer 71 to a control circuit 72 for operating the present invention. Connected across the circuit 72 is a proximity switch 74, which is operated by a probe 76 connected to the switch 74 by suitable electrical wiring 77. The proximity switch 74 may be a Go-Tronic model 71-100-115, manufactured by General Equipment and Manufacturing Co., 3360 Fern Valley Road, Louisville, Kentucky 40213. The characteristics of the proximity switch 74 are such that whenever a metallic object passes near the probe 76, the proximity switch 74 will close an internal contact pair 78. It may be seen that the contact pair 78 is connected across the ladder circuit 72 in serics with a coil TR-l of a time delay type relay. The coil TR-I controls a contact pair lTR-l, which is connected in series with a coil CR-l ofa conventional type relay. The characteristics of the relay controlled by the coil TR-l are such that the contact pair lTR-l will remain closed a short period of time after the coil TR-l has been de-energized. This time may vary, but advantageously may be set within the range of to seconds. Connected in parallel with the contact pair lTR- 1, and also in series with the coil CR-l, is a manual, normally open, push button type switch 80. The coil CR-l controls a contact pair lCR-l connected in series with a coil SV-l, which controls the operation of the solenoid valve 58. i

To summarize, the internal porting of the valves 36 and 58 is as follows: When the operating stem '34 of the valve 36 is depressed, the first inlet port is connected to the first outlet port, the second inlet port is connected to the second outlet port, and the third inlet port is blocked. When the operating stem 34 of the valve 36 is released, the spring in the valve 36 causes a shift in the connections such that the first inlet port is connected to the second outlet port, the third inlet port is connected to the second outlet port, and the second inlet port is blocked. With respect to the solenoid valve 58, when the valve is de-energized, the spring with the valve causes the internal connections to be such that the first inlet port is connected to the first outlet port, the third inlet port is connected to the second outlet port, and the second inlet port is blocked. When the solenoid valve 58 is energized, the connections shift, and the first inlet port is connected to the second outlet port, thesecond inlet port is connected to the first outlet port, and the third inlet port is blocked.

The operation of these circuits may now be described with reference to FIGS. 4, 5 and 6 as follows: When the operator of the corrugated paperboard machine splices a new roll of paper into the operation, he will place a small piece of a metallic foil tape adjacent to the spliced area. Once the spliced area has been made into corrugated paperboard and slit, it will be moving along the upper or the lower bridge of the machine. The probe 76 of the proximity switch 74 will be positioned adjacent the bridge over which the corrugated paperboard is traveling, and when the metallic foil passes the probe 76, it will generate a signal in the proximity switch 74 closing the contact pair 78. This, in turn, will energize the coil TR-l and cause the contact pair lTR-l to close. This, in turn, will energize the coil CR-l, which will cause the normally open contact pair ICR-l to close, thereby energizing the coil SV-l and energizing thesolenoid valve 58 to switch the flow path to that shown in the right-hand block in FIG. 3. As an alternative to this, it should be pointed out that the switch 80 may be closed manually by the operator of the corrugated paperboard machine and held closed until such time as the sheets of corrugated paperboard containing the splice have been rejected. It should be apparent that closing the switch 80 will have the same 7 placed adjacent to the splice area. It should be realized now that with the solenoid valve 58 energized, the flow of air is now directed along the pipelines 66 and 68 into the valve 36. However, at this time, the pipeline 68 is still connected to a blocked port of the valve 36, and there is no net flow of high-pressure air. This then means that the flow ofhigh-pressure air into the air motor 16 has ceased, and the low-pressure air entering through the pipeline 52 will begin to move the piston 50 to the right, with reference to FIG. 3. This, in turn, will extend the rod 18 and begin to pivot the sheet lifting arm 24. However, the weight of the sheets of corrugated paperboard are such that the air pressure into the air motor 16 is insufficient to allow a complete pivoting of the sheet lifting arm 24. The sheet lifting arm 24 is allowed to reach only about the position shown in FIG. 5. The position shown in FIG. 5 may be considered to be a sensing position which is intermediate the rest position shown in FIG. 4 and the active position shown in FIG. 6. This position is approximately in the same horizontal plane as the horizontal plane of travel of the sheets of paperboard. In this position, the foot portion 25 does not interfere significantly with the flow of corrugated paperboard along the lower bridge, but rather just touches the sheets of paperboard. However, as the individual sheets of paperboard leave the foot portion 25, the pressure within the air motor 16 is sufficient to fully extend the operating rod 18. When this occurs, the sheet lifting arm 24 may pivot completely upward, as seen in FIG. 6, to the point where it will divert sheets of corrugated paperboard containing the splices into the sheet removing mechanism shown in the aforementioned pending application no. 228,018. This may be considered to be the active position of the sheet lifting arm 24. It'may also be seen from FIG. 6 that as this occurs, the operating stem 34 of the valve 36 is pushed upward by the action of the spring within the valve 36, since the cam 30 is moved off the cam follower 32. This causes a shifting of the porting within the valve 36 to the porting shown on the left side of the valve 36 in FIG. 3. In this configuration, the high-pressure air introduced through the pipeline 68 is connected to the pipeline 52, which leads to the blind end of the air motor 16. This, in effect, locks the operating rod 18 in the out position by holding the piston 50in the fully forward position. This is necessary to prevent the following sheets of corrugated paperboard from pressing the piston 50' back again, since, as it was noted, the weight of the corrugated paperboard itself is sufficient to prevent the piston 50 from moving fully forward when only the low-pressure air furnished through the pipeline 49 is available to move the piston 50.

The metallic foil on the spliced area of the corrugated paperboard will give only a momentary pulse in the proximity switch 74, and the terminal pair 78 will thus open rather rapidly. This will, of course, de-

energize the coil TR-l. Therefore, the contact pair lTR-l will immediately begin to be timed to open. During this period of time, the sheets which contain the spliced areas will be rejected. After the preset period of time has elapsed, the contact pair lTR-l will open, thus de-energizing the coil CR-l and causing the contact pair lCR-l to also open. When the contact pair lCR-l opens, the solenoid valve 58 will be deenergized again to assume the configuration shown in FIG. 3. In this configuration, it may be appreciated that the high-pressure air furnished through the pipeline 63 to the valve 36 cannot function to operate the air motor 16, since the inlet to the valve 36 to which the pipeline 63 is connected is blocked so long as the valve 36 is shifted. Thus, the only input available to the air motor 16 is that furnished by the lowpressure air furnished through the pipeline 64 to the right side of the piston 50. Prior to this, the high-pressure air furnished.

through the piepeline 52 has served to keep the piston 50 toward the right, as seen in FIG. 3. However, when this air pressure is lost, due to the shifting of the valve 58, the low-pressure air furnished through the pipeline 49 will retract the rod 18 or move the piston 50 to the left with reference to FIG. 3. This, of course, will pivot the sheet lifting arm 24 and cause the foot portion 25 to be retracted below the level of the moving corrugated paperboard sheets. Once the cam 30 has reached the position seen in FIG. 5, the valve 36 will be shifted and the high-pressure air, through the pipeline 63, will again be directed to the right side of the piston 50, causing the piston 50 to assume its fully retracted position, the rest position of the entire mechanism illustrated in FIG. 4. The device is now ready to once again go through the sequence of operations to ultimately reject a sheet of corrugated paperboard which exhibits a splice upon command from the sensing of the metal strip or from the operator initiated switch, whichever mode of operation is in use.

FIG. 7 illustrates the general operational environment of the sheet deflecting mechanism of the present invention. It may be appreciated that the area shown in FIG. 7 is only a portion of the entire bridge area of a corrugator. In general, the area shown in FIG. 7 may be a part of either the upper bridge of the lower bridge, as more specifically described in the aforementioned U.S. Application Ser. No. 228,018. A plurality of sheets of corrugated paperboard material 82, 83, 84, 85, 86 and 87 are shown in phantom lines to avoid obscuring the sheet deflection mechanismslO. The sheets 82 through 87 shown in FIG. 7 clearly illustrate the stair step pattern, which was mentioned previously, of the longitudinally spaced gap between successive sheets of paperboard. The bridge structure itself has been cut away in FIG. 7, but it should be realized that a substantial supporting structure runs along either side of the lower bridge and actually forms a supporting member for the conveying system shown in FIG. 7. Mounted on a rotatable drive shaft 90 are a plurality of drive rolls 92. The drive shaft 90 is mounted on the bridge side structure in a conventional manner not shown. The drive shaft 90 extends across the entire width of the bridge and is driven by a suitable drive means not shown, to move the sheets of paperboard from left to right as seen in FIG. 7. The drive rolls 92 are spaced apart across the width of the bridge along the drive shaft 90 and are turned by the drive shaft 90.

It should be recognized that at the opposite end of the bridge is located an idler shaft and a series of idler rolls similar to the drive shaft 90 and drive rolls 92. Trained around the drive rolls 92 and the idler rolls are a plurality of endless driven belts 94. The driven belts 94 form a conveying surface on which the sheets of corrugated paperboard material 82 through 87 rest as they are conveyed away from the knives toward a stacking and sorting area. At the end of the bridge, a removal conveyor 96 is provided to convey the sheets of corrugated material to their final destination. The removal conveyor 96 typically has an endless belt 98 trained about an idler roll 99, which is mounted on a rotatable idler shaft 100. The idler shaft 100, of course, is mounted on the structure of the bridge, which is not shown in FIG. 7. At the opposite end of the removal conveyor 96 is a corresponding drive roll and drive shaft to power the belt 98. It is in this area, where the plurality of driven belts 94 end and the sheets of corrugated material are transferred onto the removal conveyor 96, that the deflection mechanism for removing sheets of corrugated material which exhibit a splice is located and shown in U.S. Pat. Application Ser. No. 228,018. The support member 12 is attached to both sides of the bridge supporting structure and extends across the entire width of the bridge. Fixed to the support member 12 at intervals are a plurality of deflection mechanisms 10, attached to the support member 12, as previously explained with respect to FIG. 1. It may readily be seen that the deflection mechanisms 10 are all located between the driven belts 94, such that the sheet lifting arms 24 of all of the sheet deflection mechanisms 10 may pivot upwardly to contact sheets of corrugated material which are being carried by the driven belts 94. In one specific instance, in a corrugator where the total width of all of the sheets of corrugated paperboard across the bridge could be no more than 87 inches, a total of nine sheet deflection mechanisms 10 were spaced evenly across the width of the bridge along the support member 12.

What I claim is:

1. Apparatus for'individually diverting sheets of corrugated paperboard moving in a substantially horizontal plane in a longitudinally spaced-apart pattern along at least one bridge of a corrugator comprising, in combination: a plurality of sheet lifting arms pivotally mounted below the horizontal plane of travel of said sheets in a substantially linear array across the width of said bridge, said lifting arms having a rest position below the horizontal plane of travel of said sheets, an active position interfering with the plane of travel of said sheets, and a sensing position intermediate said rest and active positions; power means for pivoting said lifting arms; and control means connected to said power means for: a. holding all of said lifting arms in said rest position, b. substantially simultaneously moving all of said lifting arms into said sensing position when sheets are to be diverted, and c. individually moving said lifting arms into said active position in response to a gap between successive sheets of paperboard to thereby divert sheets of paperboard from their normal plane of horizontal travel.

' 2. The apparatus of claim 1, wherein said power means comprises a plurality of reciprocating air motors.

3. The apparatus of claim 2, further including: means for individually pivotally mounting said plurality of air motors adjacent each of said lifting arms; a slidable piston contained within each of said air motors; an extensible operating rod attached to and movable with each of said pistons; and means for pivotally attaching the extending end of said operating rod to the lifting arm with which it is associated.

4. The apparatus of claim 3, wherein said control means includes: a source of low-pressure air; a source of high-pressure air; means for connecting said source of low-pressure air to all of said reciprocating air motors, the pressure of said low-pressure air being such that the net force exerted on said pistons by said low pressure air is less than the net downward force of said sheets of paperboard on said lifting arms; and, means for connecting said source of high-pressure air to all of said reciprocating air motors, the pressure of said highpressure air being such that the net force exerted on said pistons by said high-pressure air is greater than the net downward force of said sheets of paperboard on said lifting arms.

5. The apparatus of claim 4 wherein said means for connecting said source of low-pressure air to all of said reciprocating air motors comprises: a plurality, equal in number to the number of said lifting arms, of fourway cam operated, spring return valves mounted adjacent to each of said reciprocating air motors, each of said cam operated valves having a first, second and third inlet port and a first and second outlet port; means for connecting said source of low-pressure air to said first inlet port of all of said cam operated valves; means for connecting said first outlet port of said cam operated valves to the side of said pistons opposite said operating rod; a movable operating stem extending from each of said cam operated valves, said cam operated valves being so constructed that when said stem is depressed, said first inlet port is connected to said first outlet port, said second inlet port is connected to said second outlet port, and said third inlet port is blocked, and when said stem is not depressed, said third inlet port is connected to said first outlet port, said first inlet port is connected to said second outlet port, and said second inlet port is blocked.

6. The apparatus of claim 5, wherein said control means further includes: a plurality of cam followers, one cam follower being mounted on each of said operating stems; and a plurality of cams, one cam being positioned on each of said lifting arms to engage said cam followers and hold said stems depressed.

7. The apparatus of claim 5, wherein said means for connecting said source of high-pressure air to all of said reciprocating air motors comprises: a four-way, electrical solenoid operated, spring return valve, said solenoid valve being de-energized when said lifting arms are in said rest position, said solenoid valve having a first, second and third inlet port and a first and second outlet port; means for connecting said source of high-pressure air to said first inlet port of said solenoid valve; means for connecting said first outlet port of said solenoid valve to said second inlet port of all of said cam operated valves, said solenoid valve being so constructed that when said solenoid valve is de-energized, said first inlet port is connected to said first outlet port, said third inlet port is connected to said second outlet port, and said second inlet port is blocked, and when said solenoid valve is energized, said first inlet port is connected to said second outlet port, said second inlet port is connected to said first outlet port, and said third inlet port is blocked; and means for connecting said second outlet port of said cam operated valves to the side of said pistons to which said operating rods are attached.

8. The apparatus of claim 7, wherein said control means further includes: means for connecting said second outlet port of said solenoid valve to said third inlet port of all of said cam operated valves; and electrical circuit means connected to said solenoid valve for energizing and de-energizing said solenoid valve.

9. The apparatus of claim 8, wherein said electrical circuit means includes sensing means for initiating the energization of said solenoid valve; and means carried by said sheet for activating said sensing means when diversion of a sheet is desired.

10. Apparatus for selectively, upwardly, diverting sheets of corrugated paperboard from a bridge ofa corrugator, comprising a plurality of deflector members positioned at spaced intervals across the width of the bridge and normally below the path of travel of the sheets, poweroperated, deflector-actuating means connected to each of said deflector members for moving said deflectors upwardly into sheet-contacting position and means responsive to further movement of any individual deflector member to a predetermined upward position for maintaining said deflector member in fullyup, sheet deflecting position.

11. The apparatus of claim 10, further including timing means connected to said deflector-actuating means for effecting retraction of said deflector member after a predetermined period of operation.

12. The apparatus of claim 10, further including sensing means connected to said deflector-actuating means, and means carried by the sheet for activating said sensing means when deflection of a sheet is desired.

13. The apparatus of claim 10, in which said deflector-actuating means comprises an air-operated, reciprocated piston, motor and a source of air under pressure.

14. The apparatus of claim 13, wherein said means responsive to further upward movement of said deflector means, comprises a cam-actuated valve between said air source and saidmotor, and cam means carried by said deflector for operating said valve in response to movement thereof to a predetermined position.

15. A method for individually diverting sheets of corrugated paperboard moving in a substantially horizontal plane in a longitudinally spaced-apart pattern along at least one bridge of a corrugator comprising the steps of:

a. simultaneously moving a plurality of sheet lifting arms arranged in a substantially linear array across the width of said bridge from a first position below the horizontal path of travel of said sheets to a second position in contact with the underside of said sheets;

b. maintaining said lifting arms in said second position;

c. individually moving said lifting arms from said second position to a third position interfering with the horizontal path of travel of said sheets as a gap between sheets occurs;

d. holding said lifting arms in said third position with a force greater than the net downward force of said sheets; and thereby e. diverting sheets from their horizontal path of travel by contact with said held lifting arms.

16. The method of claim 15, further including the steps of:

f. substantially simultaneously moving all of said lifting arms from said third position to said first position after diverting as many sheets as desired; and

g. holding all of said lifting arms in said first position. 

1. Apparatus for individually diverting sheets of corrugated paperboard moving in a substantially horizontal plane in a longitudinally spaced-apart pattern along at least one bridge of a corrugator comprising, in combination: a plurality of sheet lifting arms pivotally mounted below the horizontal plane of travel of said sheets in a substantially linear array across the width of said bridge, said lifting arms having a rest position below the horizontal plane of travel of said sheets, an active position interfering with the plane of travel of said sheets, and a sensing position intermediate said rest and active positions; power means for pivoting said lifting arms; and control means connected to said power means for: a. holding all of said lifting arms in said rest position, b. substantially simultaneously moving all of said lifting arms into said sensing position when sheets are to be diverted, and c. individually moving said lifting arms into said active position in response to a gap between successive sheets of paperboard to thereby divert sheets of paperboard from their normal plane of horizontal travel.
 2. The apparatus of claim 1, wherein said power means comprises a plurality of reciprocating air motors.
 3. The apparatus of claim 2, further including: means for individually pivotally mounting said plurality of air motors adjacent each of said lifting arms; a slidable piston contained within each of said air motors; an extensible operating rod attached to and movable with each of said pistons; and means for pivotally attaching the extending end of said operating rod to the lifting arm with which it is associated.
 4. The apparatus of claim 3, wherein said control means includes: a source of low-pressure air; a source of high-pressure air; means for connecting said source of low-pressure air to all of said reciprocating air motors, the pressure of said low-pressure air being such that the net force exerted on said pistons by said low-pressure air is less than the net downward force of said sheets of paperboard on said lifting arms; and, means for connecting said source of high-pressure air to all of said reciprocating air motors, the pressure of said high-pressure air being such that the net force exerted on said pistons by said high-pressure air is greater than the net downward force of said sheets of paperboard on said lifting arms.
 5. The apparatus of claim 4, wherein said means for connecting said source of low-pressure air to all of said reciprocating air motors comprises: a plurality, equal in number to the number of said lifting arms, of fourway cam operated, spring return valves mounted adjacent to each of said reciprocating air motors, each of said cam operated valves having a first, second and third inlet port and a first and second outlet port; means for connecting said source of low-pressure air to said first inlet port of all of said cam operated valves; means for connecting said first outlet port of said cam operated valves to the side of said pistons opposite said operating rod; a movable operating stem extending from each of said cam operated valves, said cam operated valves being so constructed that when said stem is depressed, said first inlet port is connected to said first outlet port, said second inlet port is connected to said second outlet port, and said third inlet port is blocked, and when said stem is not depressed, said third inlet port is connected to said first outlet port, said first inlet port is connected to said second outlet port, and said second inlet port is blocked.
 6. The apparatus of claim 5, wherein said control means further includes: a plurality of cam followeRs, one cam follower being mounted on each of said operating stems; and a plurality of cams, one cam being positioned on each of said lifting arms to engage said cam followers and hold said stems depressed.
 7. The apparatus of claim 5, wherein said means for connecting said source of high-pressure air to all of said reciprocating air motors comprises: a four-way, electrical solenoid operated, spring return valve, said solenoid valve being de-energized when said lifting arms are in said rest position, said solenoid valve having a first, second and third inlet port and a first and second outlet port; means for connecting said source of high-pressure air to said first inlet port of said solenoid valve; means for connecting said first outlet port of said solenoid valve to said second inlet port of all of said cam operated valves, said solenoid valve being so constructed that when said solenoid valve is de-energized, said first inlet port is connected to said first outlet port, said third inlet port is connected to said second outlet port, and said second inlet port is blocked, and when said solenoid valve is energized, said first inlet port is connected to said second outlet port, said second inlet port is connected to said first outlet port, and said third inlet port is blocked; and means for connecting said second outlet port of said cam operated valves to the side of said pistons to which said operating rods are attached.
 8. The apparatus of claim 7, wherein said control means further includes: means for connecting said second outlet port of said solenoid valve to said third inlet port of all of said cam operated valves; and electrical circuit means connected to said solenoid valve for energizing and de-energizing said solenoid valve.
 9. The apparatus of claim 8, wherein said electrical circuit means includes sensing means for initiating the energization of said solenoid valve; and means carried by said sheet for activating said sensing means when diversion of a sheet is desired.
 10. Apparatus for selectively, upwardly, diverting sheets of corrugated paperboard from a bridge of a corrugator, comprising a plurality of deflector members positioned at spaced intervals across the width of the bridge and normally below the path of travel of the sheets, poweroperated, deflector-actuating means connected to each of said deflector members for moving said deflectors upwardly into sheet-contacting position and means responsive to further movement of any individual deflector member to a predetermined upward position for maintaining said deflector member in fully-up, sheet deflecting position.
 11. The apparatus of claim 10, further including timing means connected to said deflector-actuating means for effecting retraction of said deflector member after a predetermined period of operation.
 12. The apparatus of claim 10, further including sensing means connected to said deflector-actuating means, and means carried by the sheet for activating said sensing means when deflection of a sheet is desired.
 13. The apparatus of claim 10, in which said deflector-actuating means comprises an air-operated, reciprocated piston, motor and a source of air under pressure.
 14. The apparatus of claim 13, wherein said means responsive to further upward movement of said deflector means, comprises a cam-actuated valve between said air source and said motor, and cam means carried by said deflector for operating said valve in response to movement thereof to a predetermined position.
 15. A method for individually diverting sheets of corrugated paperboard moving in a substantially horizontal plane in a longitudinally spaced-apart pattern along at least one bridge of a corrugator comprising the steps of: a. simultaneously moving a plurality of sheet lifting arms arranged in a substantially linear array across the width of said bridge from a first position below the horizontal path of travel of said sheets to a second position in contact with the underside of said sheets; b. maintaining said lifting arms in said second position; c. individually moving said lifting arms from said second position to a third position interfering with the horizontal path of travel of said sheets as a gap between sheets occurs; d. holding said lifting arms in said third position with a force greater than the net downward force of said sheets; and thereby e. diverting sheets from their horizontal path of travel by contact with said held lifting arms.
 16. The method of claim 15, further including the steps of: f. substantially simultaneously moving all of said lifting arms from said third position to said first position after diverting as many sheets as desired; and g. holding all of said lifting arms in said first position. 